X-ray photograph marking



March 21, 1944. c. R. LANDls E1' Al.

XRAY PHOTOGRAPH MARKING. AND METHOD, AND MEANS OF MAKING SAME 2 shets-sheet 1 Filed July 21, 1941 y afa March 21, 1944. Q R, AND|5 ET AL 2,344,823

X-RAY PHOTOGRAPH MARKING, AND METHOD, AND MEANS OF MAKING SAME 'Filed July 21; 1941 2 Sheets-Sheet 2 o o v a o o u c a o o a n o o o o o o e u a n o a o o a o a 0 o o a o o o e u e o o o e o e o o o o u' 1 o o u a e u a a 0 e a o n a o e o u o o a o a o o 0 o n a o n mvmw 2 QQ# Patented Mar. 2l, 1944 ,time

'X-RAY PHOTOGRAPH MARKING,

AND

METHOD ANDiMEANS OF MAKING SAME Clyde, E. Landisand William L. Culpepper, Chicago Ill., assignors to Don B. McCloud, Du

Quon, Ill.

Application Julywl, 1941, Serial No. 403,268-

(Cl. Z50-65) L9 Claims.

This invention relates toimprovements in X- ray photographs, Aa method o'f marking, and methodand means of making the same.

The invention also relates to a new method ofy marking X-ray photographs or pictures, technically known as radiographs or roentgenograms, in such va way `that lan 'alinement or the misalinement of certain bony :structures of the body and their spaced relationships to each other can be quickly and `accurately determined and measured, and the object thereof is .to so mark the lm or vphotograph with readily visible coordinate horizontal -and vertical markings, divisions lor lines so that .there will vbe no hiatus or broken lines in the imageA at the markings to appear as a Vbreak or defect such as in bones, but a continuousV and unbroken image where the markings or lines intersect therewith or cross the same. This is done 'by producing on the film easily discernible vertical and horizontal markings, such as lines or dots equally distanced apartv in the manner of cross section paper, such lines, however, being so produced and of such nature that they do not obliterate the details of the objects that appear in the picture.

In the past, efforts have been made to produce cross-section markings on a radiograph by 'interposing an impermeably formed grid or screen between the source of X-rays and the sensitized film, such grids or screens being made of materials impervious lto X-rays and placed adjacent or some distance from the lsensitized surface of the film. Results with such devices lare unsatisfactory because the lines produced are blurred, sometimes distorted', and the image of the object shown on the radiograph is not clearly discernible at lined intersections because vthere is vno image at such points and therefore appears as if broken or fractured,` due to the breaks or hiatuses at such points.

The technique made Vpossible by thisv invention does not Arequire anything to vbe interposed between the X-rays and the sensitized lm in addition to the body to be .X-rayed and ,an intensifying screen. The marking device is placed on one side of, adjacent, in back of or in direct contact with the film. The lines produced while easily discernible, do not obliterate the details of the image of any object appearing on the lm, yet the lines .are sharply defined without any distortion in spacing due to the sheet of the marker except preferably themarking thereon being in intiiriate,` direct `contact with the sensitized surface of the film.

In the past the practice in taking radiographs or X-ray pictures consisted of exposing the sensitized surface of a lm or plate to the direct emanation of X-rays. The sensitized surface of a film or plate consists of a layer of emulsion containing certain silver compounds which are affected chemically by X-rays and more strongly aected by light rays. Formerly this emulsion was applied to only one surface of a film or plate. In modern practice, however, both surfaces of a film are coated with this sensitized emulsion and a picture is actually described or produced on each of these surfaces so that the present day radiograph may be said to consist of two facsimile pictures exactly superimposed one on the other, separated by the cellulose non-sensitive portion of the film itself. By means of this invention it is possible to produce marking lines on only one surface of the nlm leaving the opposite surface of the film unmarked and the image thereon complete in every detail and discernible even where the marking lines cross the same. This makes the lines discernible without obliterating the image photographed.

Films having both surfaces covered with sensitized emulsion are commonly kno-Wn as dupletized films and a radiograph made on such a lm ordinarily is produced by the use of intensifying screens. The technique involves placing such a lm in a holder commonly known as a cassette. The cassette or nlm holder usually has a Bakelite or aluminum front and a removable or hinged back cover of metal such as aluminum, with means for holding the same in place or closed. It is lined front and back by intensifying screens that generate light by the impact ofA X-rays upon the calcium tungstate or other material in or coating of the screens. In practice a film is placed within a cassette in contact with the front intensifying screen after which the cover or back is closed or placed upon the cassette bringing the intensifying screen attached to thev cover in direct contact with the opposite side of the lm. The cover is then clamped in place which presses the lm between the two screens. The object to be photographed is then placed between the source of X-rays and the cassette. Nhen the X-rays are focussed upon the cassette the intensifying screens immediately emanate light which persists until or for a short interval of time after the X-rays are discontinued. The sensitized surfaces of the film are susceptible both to X-rays and light rays, therefore the image on these surfaces of the lm is obtained by two stimuli, first the direct X-rays and secondly the light generated by the intensifying screens. It is estimated that approximately eighty per cent of the photographic changes that take place on the sensitized surfaces of the film are due to the light from the intensifying screens and only about twenty per cent due to the direct X-ray emanations.

The intensifying screen on the front part of the cassette affects principally the emulsion on.

the surface of the film with which it is in contact. The light from the intensifying screen on the back of the cassette affects principallyA the emulsion on the opposite sideof the lm.

In order to produce discernible lines on one of the sensitized surfaces of the film, the present' invention provides a marker to be placed becontact with the film produces the complete picture ofthe object on the sensitized surface which I 'it'. contacts. The light from the other intensifytween the sensitized film and one of the intensifying screens used in the cassette. This marker consists of lines drawn with India ink or any other opaque material, pigment or liquid on a sheet of extremely thin transparent material such as Cellophane.' The lines on the marker should be permeable by X-rays but fairly or substantially impermeable to ordinary light rays. Thus, when a marker of this sort is interposed between one of the screens, preferably Yat `the back'and the sensitized film, both screens and the film are exposed to the X-ray emanations exactly as they would be if the marker were not used because neither the'Cellophane sheet nor the lines thereon constitute a barrier or screen for'the X-rays, both being easily penetrable by such rays. The secondary light produced by the intensifying screens however does not have.-

thepenetrating power of X-rays and the lines on the marker, opaque to ordinary light, will cause shadows from the secondary light emanations producing easily discernible substantially transparent lines on the sensitized surface of the film to which the marker is adjacent. The other sensitized surface of the film is practically unaffected by this marker since the entire and complete image is produced thereon even at said lines or other markings and readily distinguishable therefrom especially at the points of crossing or intersections therewith.

In making a film marker in accordance with the present invention a piece of ordinary transparent Cellophane is preferably cut slightly smaller than the intensifying screen on one side, preferably the cover of the cassette, after which horizontal and vertical intersecting coordinate markings or lines ruled or produced in any other suitable way on the Cellophane sheet using any opaque marking material, pigment or pencil, such as carbon or India ink and an ordinary drawing pen. After the ink is dried it is good practice to glue this marker to the intensifying screen on either' the front or cover of the cassette by means of four small supports of ordinary photographerspaste, one on each corner. Then, when a dupletized duplex or doublecoated film is placed in the cassette and thev cover clamped in place one sensitized surface of the film will bear directly upon one of the ini tensifying screens whereas the opposite sensitized surface of the film will be in direct contacty with the marker which, in turn, is in contact with the other intensifying screen.

Upon exposure to X-rays in accordance with the general practice the X-ray emanations are turned on for a few seconds depending upon the nature of the object to be photographed. Both intensifying screens and both the surfaces 0f.

l the lines of ink 'or dots on the marker.

ing screen that is separated from the other sensitized surface of the film by the marker passes through the 'transparent part of the marker but is blocked by the opaque markings such as These lines therefore appear upon the developed negative or film as being transparent.

As before stated-the dupletized oppositely or double coated filmv` actually consists of two facsimile pictures exactly superimposed but separated by the cellulose .body of the filmv except that the picture or image on one side is intersected by the markings.

One side of the developed vfilm exposed as hereinbefore described,has the complete picture, the other side a likepicture divided into square segments by transparent lines. The two pictures are exactly superimposed on opposite surfaces of the single lrn.- Where there are no lines the objects appear fjust as they do on any standard dupletized film, but vwhere the lines occur the images are only of approximately half the intensity because such images come fromor are produced on only one sideof the film by both rays, the other side at thelines or markings being a clear line exceptpossibly that portion developed by exposure to the X-rays. Thus,

this invention makes it possible to produce discernible markings orcross-section lines on one surface of a lm with or without-l a complete picture produced by the X-rays only exclusive of the light rays of the intensifying screen on that side, and at the same time have the other surface of the film contain the complete unmarked picture produced by both the X-rays and light rays from the intensifying screen on the other side. r

The value of markediilms of this nature is apfparent to an vanatomist. looking at the bony structure of the human body from a so to speak mechanical standpoint in determining the condition thereof. We find that it consists of numerous parts or bones held vtogether by various types of joints and other connection media and the entire body is mechanically supported by this structure. Certain parts of this structure are normallysymmetrical. I f a mis-alinement occurs it sometimes cannot be discoveredunless it is carefully compared with the placement of a `similar member on the opposite side of theV body.

deviation from. normal. relation or; condition. and relative: mis.- alinexnentorA misplacement, .so athat correction or. proper treatment can be given the.` Suchr Vmarkings. 'on` the nlm. however' patient. should'notfbe of axtypethat-would obliteratefcompletely any part offtherimage.

Further objects. and;` advantages. will appear and `be broughtv out more fully-:in the `following.

Fig. 4 Vis a section taken en the line 4-4 of;

Fig. 3;

`Fig. 5 is an elevationpofthe marking. sheet;

Fig. 6 is a section of .the marking sheet-taken on the line=6-'6 of Fig. 5;*v l

Fig. 7 is. lan elevation. of' thellm.;

Fig'. 8 is a section of the'lm taken on the line 8--8 of Fig. 7;

Fig.` 9 is an enlarged vertical section taken on the line 9-9 of Fig. 2;

Fig. 10 sis an enlarged. face view of the developed film or negative photograph and `looking toward the side having lthe .markings thereon;-

Fig. l14 is a. view of a fragmentary portion ci the developed. film .or picture, .greatly enlarged;

Fig. 12 is a fragmentary elevation .of 'a modified. form of marking sheet; and' Fig. 13 is a fragmentary elevation of la Vlm marked by the sheet shown in Fig. 12.

Referring more particularly yto the draav-ings to illustrate the construction and operation of the invention I5 designates an .X-ray, Roentgen or Crookes llamp or tube or other source of X-rayswhich is suitably 'supported for adjustment in the usual way-not necessary to be described 'herein and adapted for'taking pictures of bodies` arranged vertically or upright,..or horizontally or `in a reclining position. As indicated, .I.6represents the mid-section of a bodywith a vperson .standing in an erect position but it is to be understood. that any other part of the `body lor `any other.

object may be employed with equal facility. The

X-rays vare generally designated at |11 the body.

being interposed between the lamp .and the frame orv cassette I8 in which the lm is held during. the taking of the picture. The cassette may be supported upon suitable means such as repre'- sented at I9 with the ycassette arranged vertical-1 ly or horizontally and illustrated in :the viorxri shown as being arranged vertically with. a suit-,y

able upright at the back. This cassette consists of a rectangular frame 2l! of -somemetal as aluminum or even Bakelite which `the Kiera-yswill penetrate and' is shown of Leshaped cross; n section or rabbeted 'to kform Va seaty as indicated. l

65 may also be of aluminum or. Bakelite or other at 2I.. The front is 'closed by 'a plate 212 which material permeable to the 'X-rays. This lplate is shown flanged at 23 around the frame 20., `being ilanged over all four sides thereof and suitably fastened by pins or othervfastenings indicated at 24. On the inside ofthe front wall 0r `plate 2-2 is a cloth or felt cushion lining 25, usually Vblack y or dark the purpose oi which will be hereinafter made. apparent. 26 designatesV a .back cover which is removable or movable as 4by :hinging thesarne totheframe 2.0 through the medium of hinges 21. This back plate or cover maybe pro videdwith a cloth or; felt cushion lining 28, usually white, both linings forming pads. While the particular construction of this cassette forms no part of the present invention and therefore may" take any of the forms usual in the art, the same has been described in order to obtain a better understanding of the present invention and the method of marking films and the operation thereof. As shown, suitable means are provided to hold the back or cover 26 closed, such means being illustrated in the -form of spring holding means or fasteners in the form oi' bowed springs 29 pivoted to the cover as at 3G and having the ends thereof adapted4 to he bent down to enter grooves 3l in the inner faces of the sides of the frame 2i) by passing the same through recesses 32 also located in said sides an@` communicating with the grooves but arranged in diagonally 0p:

34 which is usually a brous or paper body coated` with calcium tungstate or some other fluorescent coating 35 which when impacted with Xrays will give o light. This may be suitably fastened to the lining 25 in a centered position in any suitable way Iby photographers paste, glue, or otherwise. A similar screen 35 is likewise attached to the lining or pad 28 carried by the back plate or cover 26 and has a similar coating 31., both coatings or the active sides of the intensifying screens facing inwardly or toward each other. Fig. 1 shows the cassette closed in side elevation and Fig. 2 looking at the back thereof, while Figs. 3 and 4 show the cassette open. In order to mark the film, a marking medium shown in the form of a sheet 38 as illustrated in Figs. 5 and 6 of` the drawings is employed. This sheet is preferably cut smaller than the screen 36 and may be made 4of some material permeable to both X-rays and light rays such as a transparency of Cellophane, glass or the like having produced thereon suitable markings shown in the form of horizontal parallel lines 39 designated along one or more margins by suitable characters such 'as from A to Z designated at di). The marking medium or sheet is also provided with parallel vertical lines 4I designated by numbers from l to`30 or otherwise as indicated at 42, thesecoordinate lines vintersecting each other at right angles and spaced one-half inch apart cr otherwise according to the size of the X-ray'photograph to be produced yor the particular object being pictured and producing squares of similar size. The supporting or carrying medium for the lines may be any transparency so long as the lines or markings are opaque to ordinary light rays but such as to pass X-rays and may be broken or dotted lines if desired. They are preferably produced on the sheet with ordinary carbon or india ink or other suitable pigment, pencil or marking material and the medial `lines may be identied as desired. As represented in Fig. 9 of the drawings, this marking sheet or medium is placed against one of lthe intensifying screens vand preferably against the intensifying surface 31 of .the `screen 36 attached to the cover'25 with the markedV black when exposed and developed and havinga' base or cellulose portion or sheet in the center with sensitized gelatin coatings 44 and 45 on op'- posite sides. After the marking sheet is placed in position on one of the intensifying screens, the film 43 is placed in position in the cassette against this sheet or the other screenand the cassette is closed while the film is protected from exposure to light or active rays in a suitable dark room and the device is then ready for exposure to the X-rays inthe manner shownv in Fig. l

of the drawings. The resultv will be aproduct as shown more particularly in Figs. and 11 of the drawings representing the lm developed withA the picture or image in the form of a negativel produced upon the sensitized coatings on' opposite sides of the lm to appear as a singleimage but in which actually one image is superimposed upon the other to produce a'highly desirable and more readily discernible photograph. v

The result is that the bone structure or object I6 will be produced upon the film in the form.y

such as represented by the outline of the' midrif or abdominal structure represented in Fig, 10` ofthe drawings in which the image is designated by the lines 46. This film is ordinarily black or dark as indicated by the lined portion 41 in Fig. 11 while the image portion 48 on both sides or sensitized co-atings of the lm are represented asbeing stippled to indicate the light or shaded portion of the image on the film. The 'hori-i zontal markings or cross-section lines are desig nated at 49 as produced by the'lines 39 on the marking sheet and 5i) designates the image at points of intersection on one side of the film, preferably at the back where the lines intersect the image or representations of the bones and which is somewhat lighter than the portions 48.

The vertical markings or transparentlines 5|v produced by the vertical lines 4| intersect the lines 49 at right angles in the same relation as the cross-section or coordinate lines of the markings, medium or sheet and the stippling at 'the points of intersection of the lines with the image is made lighter to bring out the distinction beL tween the same and points where no markings are produced but without disturbing the continuity of the image or outlines thereof.

In producing the image, the X-ray is turned on for a few seconds to direct the same or emanations therefrom toward the film through the body I6 Aand then the X-ray lamp is turned olf. These rays impacting with the calcium tungstate or'- other luminescent coating of the intensifyingscreens causes the latter to give off light rays,

one screen causing the same to be directed toward the lm at one side in direct contact therewith while the rays on the other side Yare directed toward the film through the sheet the linesof which are opaque to ordinary light rays but permeable to X-rays so that the photographed image on thelm is obtained by two stimuli, one being the direct X-raysendthe other being the: iight generated in opposite directions by the intensifying' screens.` Since thefX-rays only produce a vminor portion or degree of development of the image' on the filmfand the light rays from the screens produce the major portion thereof, the image will be fully developed on one side where there is no marking sheet o1' medium but on the opposite side where the marking sheet-or medium such as the opaque lines is interposed between the screen and the lmor the coating thereof at .that side, the light rays from said screen will be prevented from passing to the iilm and the result is that the film will be undeveloped or un-I exposed to the light rays of said screen and the lines will :be produced'iupon the sensitive vcoating at that sideoftherfilm in the form of transparencies which are readily visible vupon viewing the lm toward a light. Thus, the image will only be developed on this side at points not intersected by the markings but since the lm` has been partially developed by X-rays on both sides due tothe markings bein-g 1' permeable tol said X-rays and the image developed by the light rays from the intensifyingscreen on the side opposite the location'of the markings, a complete image will be developed on one side and the light rays from the intensifying screen` Will develop the image at the portions not. intersected by the markings onthe side havingthe markings so as not :only to'produce the eiect'of two superimposed images but the continuity of the latter and the outlines-.thereof will be unbroken even at the markings vthus rendering the reading more accurate and :avoiding the appearance of breaks or fractures in the image or bonestructure such as appears -.with the;old method of marking.

From an observation of the X-ray picture outlinedeinl Fig. 10 of the drawings,v it will be'seen that 'mis-alinements are readily discernible by comparison of parts of the image or bonestructure-'with the calibrated or coordinate markings in this form shown as lines and reference may .be had to the calibrations 40F and 42F or letters and numbers designating the diierent lines from A to Z, and' 1"'to 30, respectively, in describing a part or locating any mis-alinement and measur ing the same; As represented,y it will be noted thatv with a line extending medially and vertically of the spine structure, the ilium o r upper part of the dorsal boneat the right hand sideis approximately one-half inch higher than that at the left hand side. Markings 52 and 53 may be provided'upon the film to indicate the right and left hand sides of the'bodyfandrthes'e may be produced'inany suitableway, .by the old method or by the tmethod'herein'4 described through the medium of the' marking sheet so that/they will be depicted on the lm in the manner illustrated. It will also be noted that other parts including the hip joints are correspondingly mis'- alinednot only as to height but also shifted vto one side or to the right'as indicated by the parting "at the pelvic bonesand thus a specialist mayA readily measure and determine the degree of misalinement and prescribe the necessary treatment for correction. Suitable data as indicated atv 54 may be written with'white ink or otherwise marked 'on the lml to identify the person orVv thateinstead of having the coordinate lines as'v shown anddescribed in Figs. 5, -and511, broken or dotted lines r39a, and Alafare yprovided :and produced by dots at the points ,of intersectionof the rectangular or square'divisions which would ordinarily be produced `by .the lines. In other words, the markings are. simply dots at the corners of the squares and Ymisalinement -canlce readily followed from such marking-.withless obscuring of `the .imageion the lm than results from solid lines or obliterating the image photographed. .It is to .be understood that `the control of the Eil-rays, the duration of use thereof and thecompletion of thepicture willbe consequently hastened by the method herein described and yet produce very clear photographs or images on the film together with the ,markings for determining space relationships `of bony structures of the body-accurately .and quickly. The method of developing -will be the same as any Well known methodypreviously practiced.

Thus, instead of employing the old method ci' applying cross-section markings on a radiograph by interposing an impermeable screen between the source of X-rays and thus the body being X-rayed or photographed and the sensitized film using screens made of material impervious to X-rays such as grids with lead lines and placed adjacent to or some distance from the sensitized surface of the fihn with resulting unsatisfactory markings lbecause the lines produced are blurred and the image of the object shown on the radiograph not discernible at all or clearly discernible at line intersections because the continuity of' the image is entirely broken by the lines or other markings in View of the fact that no photograph or development of the image appears at such points, the present invention overcomes such objections and results in a much clearer image the continuity of the body and margins `of which are entirely unbroken. The invention does not require the interposition of an X-ray impermeable marking between the source of the X-rays and the sensitized film and therefore the lines produced while easily discernible do not obliterate or cause breaks in the continuity of the body or margins .but render the same continuous and the details of the image of any object are sharply dened due to the marker being in direct ntimate contact with the sensitized surface of the film. While it is not new to use a film or plate coated on both sides with a layer of emulsion containing certain silver compounds or other sensitized coating and subjecting the same to the direct emanations of X-rays or using intensifying screens which act upon the sensitized surfaces of the nlm after the impact of the X-rays thereon, it is new to interpose a marking medium between a sensitized screen and a surface of a lm so that the light rays from such screen thrown against the marking sheet with the markings thereon opaque, impervious or impermeable to the light rays from the screen, though permeable to the X-rays, to produce the markings on the nlm which appear substantially as transparencies on one side. The result is that the image developed by the X-ray on that side is partially visible in addition to the visibility of the image fully developed on the opposite side of the film and uninterrupted by any markings as produced both by the X-rays and the light rays from the sensitized screen at said side.

While we have illustrated and described the preferred form of construction for carrying our invention into effect, this is capable of variation and modification without departing from the spirit :ofthe invention. We, therefore, do not wish toibe limited `to :thez precise detailsv of con- -structionfsetr forth, :but .desire to avail ourselves of such variations and modifications as come within the scopev of the `appended claims.

` Having thus sdescribed our invention, what `we .claim asrnew and desire Lto secure by Letters Patentiisi 1. A method of marking double coated lms `'consisting ininterposing the film between two intensifier screens ,adaptedtoggive olf light when impacted by X-rays througha Vbody to-be pictured and interposing betweenonly one -of the screens and the lm a transparent marking sheet having intersecting vertical and horizontal markings thereon of anarea to extend overthe imagepictured on the film produced b y material pervious to X-rays but impervious to light rays from the screen whereby .theimage .of the object v,produced willbe produced upon both ysides of the ,film by fthe X-rays, completelyv on one side by the light rays from the intensifier screen at that side and on the other side by the light rays from the other intensifier screen except at the interception of the light rays from said screen by the lines so as to produce lines on the film at said side only in the form of transparencies.

2. An X-ray iilin having a sensitive coating on both sides and superimposed images of the object produced on both of said sides by X-rays and light rays, the image on one side only as produced by the light rays at said side being intersected by transparent markings produced by material impermeable to light rays and interposed between the film and said light rays.

3. An X-ray film or photograph having sensitized coatings on both sides bearing an image lof an object X-rayed, such as bone structure, and parallel lines normal to each other in the form of transparencies on one side only of the lm superimposed over complete and partial development of the image to present an unbroken outline of the image between and at the line intersections.

4. A method of marking the entire object area of a film as used in making radiographs to determine alignment or misalignment and spaced relationship to each other oi' bone structure or parts of the object X-rayed consisting in interposing a film between a pair of sensitized screens, interposing between one side of the film and only one of the screens, a normally transparent sheet having coordinate lines thereon opaque to ordinary light rays but transparent to X-rays, ovei' the image area, and exposing the same, whereby said lines will appear on the lrn over a partially developed image as transparencies.

5.` A method of marking the entire object area of a film as used in making radiographs to determine alignment or misalignment and-spaced relationship to each other of bone structure or parts of the object X-rayed consisting in interposing a film between a pair of sensitized screens, interposing between one side of the film and only one of the screens, coordinate lines opaque to ordinary light rays but transparent to X-rays, over the image area, and exposing tne same, whereby said lines will appear on the film over a partially developed image as transparencies.

6. A method of marking an X-ray film over the entire area thereof, with coordinate lines appearing on one side only over the object pictured thereon, consisting of interposing a transparent marking medium in the form of a sheet of substantially the same size as the lm, having coordinate lines thereon opaque to ordinary light rays and transparent to X-rays, between one side of the film and only one intensifying screen as used in X-raying an object wherein the lm is interposed between two intensifying screens. in a cassette, and leaving the opposite side of the film unobstructed to light rays from the other screen. Y v

7. A duplex Iilm having transparent markings thereon on one side only and intersecting at right angles over an image produced on the lm, said markings consisting of intersecting lines and the image being complete at all points including the points of intersection, and visible in marked contrast to the lines at the points of intersection, whereby the image of the object photographed will be complete at all points.

8. A method of marking the image area of an Xeray film with coordinate transparent lines consisting in exposing to X-rays which have passed .through Vthe object' being photographed, an assembly of said X-ray 1m,'an intensifying screen and a marker interposed therebetween, said Vmarker being adjacent a sensitized surface of said lm and having over its surface adjacent said image area coordinate lines opaque to ordinary light but transparent to X-rays.

9. A method of marking the image area of an X-ray film with coordinate transparent lines consisting in exposing to X-rays which have passed through the object being photographed, an assembly of said X-ray lm,` an intensifying screen and Ia marker interposed therebetween, said marker being adjacent a sensitized surface of said lm and having over its surface adjacent said image area coordinate lines opaque to ordinary light but transparent to X-rays, said lines intersecting each other at right-angles.

CLYDE R. LANDIS. s WILLIAM L. CULPEPPER. 

